The present invention generally relates to an electrochemical cell and battery and, more particularly, to an electrochemical cell and an assembly of multiple cells in a rectangularly housed battery.
Conventional alkaline batteries commonly employ cylindrical cells, each generally having a cylindrically shaped steel can provided with a positive cover at one end and a negative cover at the opposite end. The cylindrical cell often includes a cathode preferably formed of a mixture of manganese dioxide, graphite, potassium hydroxide solution, deionized water, and a TEFLON(copyright) solution, formed about the interior side surface of the cylindrical steel can. A cup-shaped separator is usually disposed about the interior surface of the cathode. An anode, typically formed of zinc powder, a gelling agent, and other additives, is dispensed with electrolyte solution within the separator.
Standard alkaline cells are commercially available for providing an open circuit voltage of about 1.5 volts. When a higher voltage is required, it is common practice to combine multiple cells to form a battery having the required voltage. In so doing, a plurality of cells are commonly housed in a container and connected in series, with external terminals attached to the container and making contact with the series connected cells. In particular, the standard rectangular-housed, 9-volt battery, which is commonly used in smoke detectors and portable electronic devices, includes six, 1.5-volt cells connected in series. One example of a rectangular battery employs two stacks of three cylindrical cells disposed parallel to each other as is disclosed in U.S. Pat. No. 4,959,280 entitled xe2x80x9cBattery Assembly,xe2x80x9d which is hereby incorporated by reference. It is also known to employ six, 1.5-volt cylindrical cells arranged in parallel with each other in a 2xc3x973 array. However, the use of multiple, parallel disposed cylindrical cells housed together within a rectangular container results in unused space between adjacent cells, as well as between each cell and the inside walls of the battery container.
A primary goal in designing alkaline batteries is to increase the service performance of the cell. The service performance is the length of time for the cell to discharge under a given load to a specific voltage at which the cell is no longer useful for its intended purpose. Commercially available alkaline cells and batteries commonly have an external size that is defined by industry standards, thereby limiting the ability to increase the amount of active materials within a given cell and confining the volume available in a multiple cell battery. However, conventional batteries often do not optimize volume consumption within the housing of the battery. Accordingly, the need to find new ways to increase service performance remains the primary goal of the cell and battery designers.
The present invention improves the performance of a cell and a rectangularly housed, multiple cell battery by providing the cell with a prismatic can, preferably of a rectangular configuration, having an open end to accommodate a cover. To achieve this and other advantages, and in accordance with the purpose of the invention as embodied and described herein, the present invention provides an electrochemical cell which includes a prismatic conductive container configured to have a substantially prismatic section, such as a rectangular section, and sidewalls, a closed bottom end and an open top end that is closed with a cover. The prismatic section houses the active materials of the cell including positive and negative electrodes, as well as a separator. The first electrode is disposed in the container substantially within the prismatic section and is disposed against inner walls of the conductive container such that the first electrode conforms to the prismatic section of the conductive container. The second electrode is disposed within an inner cylindrical volume of the prismatic section of the container. The cell is preferably assembled with a cover and seal assembly provided on the open top end of the container.
According to a further aspect of the present invention, a plurality of prismatic cells, such as rectangular cells, are assembled in a housing, such as a rectangular housing of a multiple cell battery. The cells are each configured with a prismatic section, such as a rectangular section, to allow multiple cells to be assembled close together and thereby optimize volume consumption within the battery housing.